Common Signs of a Water Main Break Sometimes, a leak or break in the water has no obvious signs, while other times it can be quite dramatic. The average cost of a repair of a moderate leak without needing to replace the line is around $800. The average cost to replace your water main line is approximately $2,500, depending on the location of your water main and the length of pipe being replaced. Only part of the expense of water main repair is the repair of the main itself. An equal or larger part of the cost of the repair is often fixing the damage caused by the leak. If your break is past the point of repair, replacing your water main line will need to happen. The key is to look for any of the following: If your water main line is far away from your home, then you can expect the cost of your replacement to be closer to $5,000. A break in the main can cause flooding in your yard, and many times all water entering the house will be contaminated. Main Water Line Leak. Cost to Fix a Burst Water Main Line Replacing just the broken section of pipe usually costs $500-$1,000. If you carefully monitor your family's water usage you can catch problems or leaks in the water main before they are insurmountable. Repairing a main water line leak will cost between $450 and $2,500 depending on if it needs to be replaced or not. The main water line is responsible for bringing water to your home from the city line.